The invention relates to a system of components, which, when assembled, form a rainwater separator for a downpipe. The system consists of                a cylindrical screen,        a cylindrical housing tube,        a ring-shaped lid having an inlet connection for the rainwater,        a ring-shaped collecting basin, having an inside wall and an outside wall and forming a central water outlet.        
The dimensions of the screen, of the housing tube, of the ring-shaped lid and the collecting basin are selected, so that, in a first assembly arrangement, they can be arranged so that                the screen is arranged in the housing tube concentrically with the longitudinal axis of the housing tube, so that an annular space is formed between the screen and the housing tube,        the annular space is sealed at its bottom by a ring-shaped collecting basin, wherein the screen sits on the edge of the inside wall,        the cylindrical inlet connection for the rainwater is arranged relative to the longitudinal axis of the screen        and its lower edge is immersed in the upper end face of the screen.        
One such rainwater separator is described in DE 38 12 136 A1. The rainwater runs down the inside wall of the downpipe and goes through the inlet connection into the cylindrical screen.
In the screen, which is preferably a fine screen, a portion of the water is drawn outward due to adhesion forces and thus, having been finely filtered, enters the annular space and goes from there into the collecting basin, which has an outlet at the side. The unfiltered water enters the central water outlet and from there enters the lower portion of the downpipe.
The water filtered in this way can be used as non-potable water in the household, e.g., for flushing a toilet or for a washing machine. However, such fine filtering through a fine screen is not always necessary. For example, coarse filtering is sufficient if the water is needed only for watering the garden, for example. Such rainwater separators are known.
The invention is based on the object of creating a system whose components can be utilized to separate both non-potable water and garden watering water from a downpipe for rainwater.
To achieve this object, the invention provides that the outside wall of the collecting basin and the upper edge of the housing tube shall have the same contour, so that the ring-shaped lid can be placed on the housing tube as well as on the outside wall of the collecting basin, so that it sits tightly, but the dimensions of the ring-shaped lid and the collecting basin are also selected, so that they can be arranged in a second assembly arrangement in such a way that the ring-shaped lid can be placed directly on the outside wall of the collecting basin, omitting the screen and the housing tube, such that the lower edge of the cylindrical inlet connection is situated radially outside of the inside wall of the collecting basin, so that the rainwater can enter the collecting basin directly.
A fine filtering is thus performed in the first assembly arrangement, so that the filtered rainwater can be used as non-potable water. The screen and the housing tube are omitted in the second assembly arrangement. Instead, the ring-shaped lid is placed directly on the collecting basin, so that the rainwater can enter the collecting basin directly—and at least is not finely filtered.
According to the invention, the ring-shaped lid fits the housing tube as well as the collecting basin, so the same parts can also be used to implement either one assembly arrangement or the other assembly arrangement. This greatly simplifies the provisioning of parts.
The yield of water is particularly great when, in the second assembly arrangement, the lower edge of the cylindrical inlet connection is inserted into the collecting basin.
In order for the water entering the rainwater separator from the downpipe to strike the screen surface, the invention provides that the screen has a conical downward taper, so that the diameter of the lower edge of the inlet connection is smaller than the largest diameter of the screen, so that in the first assembly arrangement, the lower edge of the inlet connection runs over the conical inside wall of the screen in a vertical projection.
However, it has been found that at least a coarse filtering must also be accomplished in the second assembly arrangement, so that coarse pieces, such as leaves and small branches, are not added to the collecting basin. Therefore, the invention provides that a coarse ring-shaped screen is part of the system and its dimensions are selected so that, in the second assembly arrangement, it is arranged between the lower edge of the cylindrical inlet connection and the inside wall of the collecting basin. This coarse filter may optionally be used when the rainwater is expected to be heavily loaded with large pieces.
In both assembly arrangements, the yield can be increased if the rainwater is distributed as uniformly as possible on the circumference of the inlet connection when it runs into the screen and/or onto the coarse screen. The invention therefore provides that the inside wall of the inlet connection is furnished with grooves or webs, which run helically and achieve a uniform distribution of the water flowing into the inlet connection over its circumferential area.
To achieve a large volume of the collecting basin, on the one hand, and to permit a small distance of the downpipe and the rainwater separator from the wall of the house, on the other hand, the invention provides that the outside contour of the ring-shaped lid of the housing tube and the collecting basin each have a corresponding rectangular or elliptical cross section. Fundamentally, however, a conventional round cross section may also still be selected.
The rectangle may have straight edges but may also be formed by two line segments running parallel and two convex curvatures connecting the line segments to one another.
The invention will now be explained in greater detail below on the basis of an exemplary embodiment.